Repairing A 300W CO2 Laser, One Toasted Part At A Time

June 16, 2021 by Tom Nardi 27 Comments

A couple months back, [macona] got his hands on a 300 watt Rofin CO2 laser in an unknown condition. Unfortunately, its condition became all too known once he took a peek inside the case of the power supply and was confronted with some very toasty components. It was clear that the Magic Smoke had been released with a considerable bit of fury, the trick now was figuring out how to put it back in.

The most obvious casualty was an incinerated output inductor. His theory is that cracks in the ferrite toroid changed its magnetic properties, ultimately causing it to heat up during high frequency switching. With no active cooling, the insulation cooked off the wires and things started to really go south. Maybe. In any event, replacing it was a logical first step.

If you look closely, you may see the failed component.

Unfortunately, Rofin is out of business and replacement parts weren’t available, so [macona] had to wind it himself with a self-sourced ferrite and magnet wire. Luckily, the power supply still had one good inductor that he could compare against. After replacing the coil and a few damaged ancillary wires and connectors, it seemed like the power supply was working again. But with the laser and necessary cooling lines connected, nothing happened.

A close look at the PCB in the laser head revealed that a LM2576HVT switching regulator had exploded rather violently. Replacing it wasn’t a problem, but why did it fail to begin with? A close examination showed the output trace was shorted to ground, and further investigation uncovered a blown SMBJ13A‎ TVS diode. Installing the new components got the startup process to proceed a bit farther, but the laser still refused to fire. Resigned to hunting for bad parts with the aid of a microscope, he was able to determine a LM2574HVN voltage regulator in the RF supply had given up the ghost. [macona] replaced it, only for it to quickly heat up and fail.

Now this was getting ridiculous. He replaced the regulator again, and this time pointed his thermal camera at the board to try and see what else was getting hot. The culprit ended up being an obsolete DS8922AM dual differential line transceiver that he had to source from an overseas seller on eBay.

After the replacement IC arrived from the other side of the planet, [macona] installed it and was finally able to punch some flaming holes with his monster laser. Surely the only thing more satisfying than burning something with a laser is burning something with a laser you spent months laboriously repairing.

We love repairs at Hackaday, and judging by the analytics, so do you. One of this month’s most viewed posts is about a homeowner repairing their nearly new Husqvarna riding mower instead of sending it into get serviced under the warranty. Clearly there’s something about experiencing the troubleshooting and repair process vicariously, with our one’s own hardware safely tucked away at home, that resonates with the technical crowd.

Riding Mower Repair Uncovers Miniature Culprit

June 4, 2021 by Tom Nardi 62 Comments

Most people would be pretty upset it the lawn mower they spent $4,000 USD on had a major failure within the first year of owning it. But for [xxbiohazrdxx], it was an excuse to take a peek under the hood and figure out what brought down this state-of-the-art piece of landscaping gear.

It should be said that, at least technically, the Husqvarna TS 348XD in question was still working. It’s just that [xxbiohazrdxx] noticed the locking differential, which is key to maintaining traction on hilly terrain, didn’t seem to be doing anything when the switch was pressed. Since manually moving the engagement lever on the transmission locked up the differential as expected, the culprit was likely in the electronics.

As [xxbiohazrdxx] explains, the switch on the dash is connected to a linear actuator that moves the lever on the transmission. The wiring and switch tested fine with a multimeter, but when the actuator was hooked up to a bench power supply, it didn’t move. Even more telling, it wasn’t drawing any power. Definitely not a good sign. Installing a new actuator would have solved the problem, but it was an expensive part that would take time to arrive.

Repairing the dead actuator seemed worth a shot at least, so [xxbiohazrdxx] cracked it open. The PCB looked good, and there were no obviously toasted components. But when one of the internal microswitches used to limit the travel of the actuator was found to be jammed in, everything started to make sense. With the switch locked in the closed position, the actuator believed it was already fully extended and wouldn’t move. After opening the switch itself and bending the contacts back into their appropriate position, everything worked as expected.

A tiny piece of bent metal kept this $4,000 machine from operating correctly.

As interesting as this step-by-step repair process was, what struck us the most is [xxbiohazrdxx]’s determination to fix rather than replace. At several points it would have been much easier to just swap out a broken part for a new one, but instead, the suspect part was carefully examined and coaxed back to life with the tools and materials on-hand.

While there’s plenty of folks who wouldn’t mind taking a few days off from lawn work while they wait for their replacement parts to arrive, not everyone can afford the luxury. Expedient repairs are critical when your livelihood depends on your equipment, which is why manufacturers making it harder and more expensive for farmers to fix their tractors has become such a major issue in right to repair battles all over the globe.

Aircraft Compass Teardown

May 30, 2021 by Al Williams 6 Comments

We didn’t know what a C-2400 LP was before we saw [David’s] video below, but it turned out to be pretty interesting. The device is an aircraft compass and after replacing it, he decided to take it apart for us. Turns out, that like a nautical compass, these devices need adjustment for all the metal around them. But while a ship’s compass has huge steel balls for that purpose, the tiny and lightweight aviation compass has to be a bit more parsimonious.

The little device that stands in for a binnacle’s compensators — often called Kelvin’s balls — is almost like a mechanical watch. Tiny gears and ratchets, all in brass. Apparently, the device is pretty reliable since the date on this one is 1966.

Continue reading “Aircraft Compass Teardown” →

Repairing A Vintage HP 9825 The Hard Way

May 19, 2021 by Jonathan Bennett 16 Comments

[CuriousMarc] is at it again, this time trying to undo the damage from a poorly designed power circuit, that fried the internals of his HP 9825 computer. (Video, embedded below.)

The power supply on this particular model has a failure mode where a dying transistor can lead to 13 V on the 5 V line. This causes all the havoc one would expect on the internals of a 1970s era portable computer. This particular computer is rather rare, so instead of calling it a lost cause, our protagonist decides to replace the faulty transistor, install a proper overvoltage protection circuit, and then start the tedious hunt for which chips actually let their magic smoke out.
Continue reading “Repairing A Vintage HP 9825 The Hard Way” →

A “Disgusting” 1980s Computer Restored

May 17, 2021 by Al Williams 42 Comments

It takes a special eye to see a junkyard car and envision it as your latest hotrod. The guys at RMC found what they termed a “disgusting” Acorn Electron and decided to restore it to its former glory. The Electron was a budget version of the BBC micro with a 6502 running at 2 MHz when executing code from ROM and 1 MHz when it hit the RAM. Apparently, at least some of the bus was operating at 4 bits instead of 8. Go figure.

The 1982 machine was meant to head off the Sinclair ZX and was set to sell for about £200. However, the machine didn’t catch on like the Sinclair and undersold it by around 20 times with a paltry quarter of a million units.

Continue reading “A “Disgusting” 1980s Computer Restored” →

Orphaned IoT Sleep Tracker Resurrected As An Air Quality Monitor

April 10, 2021 by Anool Mahidharia 9 Comments

If you have a Hello Sense sleep tracking device lying around somewhere in your drawer of discards, it can be brought back to life in a new avatar. Just follow [Alexander Gee]’s instructions to resurrect the Hello Sense as an IoT air quality data-logger.

In 2014, startup “Hello” introduced the Sense, an IoT sleep tracking device with a host of embedded sensors, all wrapped up in a slick, injection molded spherical enclosure. The device was quite nice, and by 2015, they had managed to raise $21M in funding. But their business model didn’t seem sustainable, and in 2017, Hello shut shop. Leaving all the Sense devices orphaned, sitting dormant in beautifully designed enclosures with no home to dial back to.

The original Sense included six sensors: illumination, humidity, temperature, sound, dust / particulate matter on the main device, and motion sensing via a separate Bluetooth dongle called the Pill. [Alexander] was interested in air quality measurements, so only needed to get data from the humidity/temperature and dust sensors. Thankfully for [Alexander], a detailed Hello Sense Teardown by [Lindsay Williams] was useful in getting started.

The hardware consisted of four separate PCB’s — power conditioning, LED ring, processor, and sensor board. This ensured that everything could be fit inside the orb shaped enclosure. Getting rid of the LED ring and processor board made space for a new NodeMCU ESP8266 brain which could be hooked up to the sensors. Connecting the NodeMCU to the I2C interface of the humidity/temperature sensor required some bodge wire artistry. Interfacing the PM sensor was a bit more easier since it already had a dedicated cable connected to the original processor board which could be reconnected to the new processor board. The NodeMCU board runs a simple Arduino sketch, available on his Git repo, to gather data and push it online.

For the online data display dashboard, [Alexander] found a nice solution by [Nilhcem] for home monitoring using MQTT, InfluxDB, and Grafana. It could be deployed via a docker compose file and have it up and running quickly. Unfortunately, such projects don’t usually succeed without causing some heartburn, so [Alexander] has got you covered with a bunch of troubleshooting tips and suggestions should you get entangled.

If you have an old Sense device lying around, then this would be a good way to put it some use. But If you’d rather build an air-quality monitor from scratch, then try “Building a Full-Fat Air-Quality Monitor” or “An Air-quality Monitor That Leverages the Cloud“.

Soviet Axe Restoration: Replace Or Repair?

April 7, 2021 by Kristina Panos 12 Comments

What do you do with a cool-looking misfit guitar that has non-working built-in effects and some iffy design aspects? Do you try to fix it and keep it original, or do you gut it and strut your stuff with new bits from around the shop? This is the conundrum that [Tim Sway] finds himself in with this late 70s/early 80s Formanta Solo II straight out of the USSR. (Video, embedded below.)

[Tim] likes a lot of things about it (and we do, too), especially the acid green pick guard, the sparkly pickups, and the beefy bridge that lets him set the string spacing individually, on the fly. It even has a built-in phaser and distortion, but those aren’t working and may never have worked that well at all.

As you can see in the video below, [Tim] has already spent a few hours making it playable and a little more palatable in order to figure out what to do with it electronics-wise. He started by making the 9 V compartment big enough to actually fit a battery inside, and drilled out bigger holes for new tuners.

Interestingly, these guitars had a 5-pin DIN receptacle instead of a 1/4″ jack. [Tim] bought an adapter just in case, but once someone dug up a schematic and sent it over, he decided to rewire it with a 1/4″.

For all of its plus sides, [Tim] doesn’t like the headstock on this thing at all and found the neck to be too chunky for the modern guitarist, so he cut down the headstock, shaved down the neck a bit, and stained it dark. He also made a new nut out of what looks like rosewood. Then it was on to the more standard stuff — file down the frets and polish them, oil the fretboard, and clean up the body.

The point of this exercise is to make a usable guitar for the modern musician. As [Tim] says, this is not a particularly valuable guitar, nor is it rare, and it wasn’t built that well to begin with. One of the issues is the switches — they’re kind of light and cheesy feeling, and one of them is directly in the strum path. Will [Tim] change those out but fix the original effects, or will he make the thing completely his own? We wait with bated breath.

Want to mess around with cheap old guitars, but don’t know where to start? Our own [Sven Gregori] has your back with Axe Hacks.